Consumer food testing device

ABSTRACT

A food testing device for testing for the presence of harmful contaminants in a food sample, includes a vessel adapted for holding a liquefied food sample, a liquefier operatively associated with the vessel for converting an unliquefied food sample into a liquefied food sample, at least one test assay dispensable from the device, wherein the test assay includes at least one assay reagent having an affinity for at least one harmful contaminant, and capable of both detecting the presence of the harmful contaminant in the liquefied food sample, and producing a visual cue upon recognition of the harmful contaminant; and a radiation detector disposed proximately to the vessel for indicating the presence of ionizing radiation in the food sample at amounts exceeding normal background levels to detect the presence of a radioactive agent as the harmful contaminant.

FIELD OF THE INVENTION

The present invention relates to safety testing of foodstuffs, and moreparticularly to a portable testing device for use by consumers to detectthe presence of harmful contaminants in foodstuff to avoid consumptionof contaminated food.

BACKGROUND OF THE INVENTION

Recent events in the world have given rise to concerns aboutunconventional terrorist attacks using biological, chemical, and/orradioactive weapons of mass destruction. These events have furtherheightened international awareness of the vulnerability of food andwater supplies of nations to terrorist attacks. Certain biological,chemical and/or radioactive agents can be used in such attacks todangerously contaminate food and water supplies. Such contamination mayhave widespread destructive effects on a large population resulting inlarge numbers of fatalities, serious acute long-term health effects suchas fetal abnormalities, paralysis, blindness, physical disfigurement,and mental debilitation, and chronic illnesses such as cancer. Thedeliberate contamination of food and water is a real and current threat.

The U.S. Centers For Disease Control and Prevention (CDC) has identifiedseveral harmful contaminants that can be critical agents for possibleterrorist attacks. Among the high-priority biological agents (“CategoryA” agents) are Bacillus anthraces (anthrax) and Clostridium botulinum(botulism), both of which are deadly pathogens and can be used tocontaminate food and water.

The majority of harmful contaminants identified by CDC were classifiedas “Category B” agents because they are moderately easy to disseminateand cause moderate morbidity and low mortality. Some of the Category Bagents include Salmonella spp. such as Salmonella typhimurium andSalmonella enteritidis, Shigella spp. such as Shigella dysenteriae,Escherichia spp. such as E. coli 0157:H7 and E. coli non-O157:H7 STEC,Campylobacter spp. such as Campylobacter jejuni, Listeria spp. such asListeria monocytogenes, and the like.

The CDC further identified certain chemicals as possible agents forterrorist attack. Those include pesticides, dioxins, furans,polychlorinated biphenyl (PCBs), cyanides, heavy metals such as arsenic,lead and mercury, and other natural and synthetic persistent toxinsincluding mycotoxin and marine toxin. The CDC has warned that terroristsmay use various combinations of these agents, and/or implement attacksin more than one location simultaneously.

These agents are also known to pose significant threat in the event thatthey are inadvertently introduced into the food and water distributionchain due to unintentional contamination of food (e.g., throughprocessing failures or handling errors) unrelated to terrorism. Majoroutbreaks of food poisoning occur all too frequently, sometimesaffecting hundreds of thousands of people.

Some examples of large-scale outbreaks caused by unintentionalcontamination include, among other incidences, an outbreak of Salmonellaenteritidis infection linked to a contaminated ice cream pre-mixsickened an estimated 224,000 people in 41 states in the U.S. in 1984,an outbreak of Salmonella typhimurium infection linked topost-pasteurization contamination of milk from a U.S. dairy plantsickened approximately 170,000 people in 1985; an outbreak of hepatitisA, which may be the largest food borne disease incident in history,caused by tainted clams affected nearly 300,000 people in China in 1991;and an outbreak of Escherichia coli 0157:H7 linked to tainted radishsprouts served in school lunches sickened about 8,000 children with somedead in Japan in 1996.

The World Health Organization (WHO) has estimated that about two millionchildren worldwide die from food and water contaminated by pathogenicmicrobes every year. In developed countries, one out of every three hassuffered from some form of a food poisoning every year. It is estimatedthat about 76 million illnesses, 325,000 hospitalizations, and 5,000deaths occur annually due to food/water contamination in the U.S.

Food poisoning from contamination with pesticides, natural and synthetictoxins, marine toxins, mycotoxins, heavy metals, cyanide, and otheracutely toxic chemicals also have been reported. In one deadly incidentin 1981, a cooking oil product sold in Spain contaminated with achemical agent that killed over 800 people and injured about 20,000. In1985, nearly 1,400 people in the U.S. reported becoming ill after eatingwatermelon grown in soil treated with the pesticide aldicarb. During1971-72, more than 6,500 people were hospitalized with neurologicalsymptoms and 459 died after eating bread made from mercury-contaminatedwheat in Iraq. Additionally, in the 1960's, more than 200 people inJapan suffered from mercury poisoning after eating highly contaminatedfish caught in polluted waters.

In today's global marketplace, the contamination of food in one countrycan have a significant effect on public health in other parts of theworld. In 1989, approximately 25,000 people in 30 states in the U.S.were sickened by Salmonella chester in cantaloupes imported from Mexico.In 1996 and 1997, 2,500 people in 21 states in the U.S. and two Canadianprovinces developed Cyclospora infections after eating taintedGuatemalan raspberries.

Accordingly, there is a need for a food testing device designed toimplement rapid real-time testing of foodstuffs prior to consumption.There is a further need for a food testing device that is compact,portable and simple to use with little or no training in laboratorytechniques. There is a further need for a food testing device that isdesigned to prevent or minimize the incidence of illness, injury anddeath caused by deliberate or unintentional contamination of food andwater.

SUMMARY OF THE INVENTION

The present invention relates generally to a consumer food testingdevice useful for implementing rapid, real-time testing of foodstuffsprior to consumption. The food testing device of the present inventionis compact and portable, and intended for use by a consumer at anylocation including their home or in a restaurant, for example. The foodtesting device of the present invention is designed to analyze anddetect in food potentially harmful contaminants including chemicalagents, biological agents and radioactive agents, and alert the userprior to consumption. The food testing device can further be adapted todetect food specific allergens that may cause the consumer to exhibiteffects of hypersensitivity or allergic reaction.

The food testing device of the present invention is capable of analyzingsmall amounts of food samples, and can be implemented by consumerswithout extensive training in laboratory techniques. The food testingdevice is simple and cost effective to construct and implement, itscompact size greatly enhances portability and discreet operation, whileeffectively acting to prevent a user from consuming contaminated food.

The food testing device of the present invention is designed to processa food sample into a form that can be tested by test assays. The testassays utilized are preferably in the form of a dipstick assay includingchromatographic assays such as flow through and lateral flow assays, orother dipstick assays. Most preferably, the test assay is a lateral flowassay in the form of a dipstick. The use of lateral flow assays yields arelatively simple one-step analysis process that can easily beimplemented by inexperienced users.

In general, a lateral flow assay typically includes an elongatedrectangular component, often of paper, nitrocellulose or other porousinert material, upon which are printed stripes or layers of assayreagents having particular affinity for a target substance (i.e.,harmful contaminant). The lateral flow assay includes a sample end,which is dipped into a sample, and the fluid is drawn along the strip bycapillary action. As the sample passes the zones of assay reagents,chemical reactions occur which may result in a visual cue or colorchange, which can be in the form of one or more stripes, for example.

In one aspect of the present invention, there is provided a food testingdevice for testing for the presence of harmful contaminants in a foodsample, which comprises:

a vessel adapted for holding a liquefied food sample; and

at least one test assay dispensable from the device, the test assaycomprising at least one assay reagent having an affinity for at leastone harmful contaminant, and capable of both detecting the presence ofthe harmful contaminant in the liquefied food sample, and producing avisual cue upon recognition of the harmful contaminant.

In a further aspect of the present invention, there is provided a foodtesting device for testing for the presence of harmful contaminants in afood sample, which comprises:

a vessel adapted for holding a liquefied food sample;

a liquefier operatively associated with said vessel for converting anunliquefied food sample into a liquified food sample; and

at least one test assay dispensable from the device, the test assaycomprising at least one assay reagent having an affinity for at leastone harmful contaminant, and capable of both detecting the presence ofthe harmful contaminant in the liquefied food sample, and producing avisual cue upon recognition of the harmful contaminant.

Preferably, the food testing device further comprises a radiationdetector disposed proximately to the vessel for indicating the presenceof ionizing radiation in the food sample at amounts exceeding normalbackground levels to detect the presence of a radioactive agent as theharmful contaminant.

In another aspect of the present invention, there is provided a methodfor testing for the presence of a harmful contaminant in a food sample,comprising the steps of:

liquefying the food sample to yield a liquefied food sample; and

implementing at least one test assay comprising an assay reagent havingan affinity for at least one harmful contaminant and capable of bothdetecting and visually indicating the presence of the harmfulcontaminant in the liquefied food sample.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings, in which like items may have the same referencedesignations, are illustrative of embodiments of the present inventionand are not intended to limit the invention as encompassed by the claimsforming part of the application, wherein:

FIG. 1 is a top plan view of a food testing device for one embodiment ofthe present invention;

FIG. 2 is a partial cross-sectional view taken along lines 2-2 of FIG. 1in accordance with the present invention; and

FIG. 3 is an exploded assembly view of a lateral flow assay for oneembodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates generally to a consumer food testingdevice useful for implementing rapid, real-time testing of foodstuffsprior to consumption, for preventing consumption of contaminated food.The food testing device of the present invention is intended for use bya consumer at any location including their home or in a restaurant. Thefood testing device of the present invention is designed to analyze anddetect potentially harmful contaminants including chemical agents,biological agents and/or radioactive agents, and alert the user prior toconsumption. The food testing device can be adapted to detect specificfood allergens that may cause the consumer to exhibit effects ofhypersensitivity or allergic reaction. The food testing device of thepresent invention is designed to analyze small amounts of food samples,and can be implemented by consumers without extensive training inlaboratory techniques.

The food testing device of the present invention ensures that the foodis safe for human consumption in a rapid, real-time manner, and issubstantially free of harmful contaminants that can be dangerous to theconsumer. The present invention operates to prevent or substantiallyminimize the incidence of food contamination due to improper handling orsabotage, while reducing the complexity of the testing process and thetime needed to implement such tests. The food testing device is simpleand cost effective to construct and implement, and its compact sizegreatly enhances portability and discreet operation.

In one embodiment of the present invention, there is provided a foodtesting device for testing the presence of harmful contaminants in afood sample, which comprises a vessel adapted for holding a liquefiedfood sample; and at least one test assay dispensable from the device.The at least one test assay comprises at least one assay reagent havingan affinity for at least one harmful contaminant, and capable of bothdetecting the presence of the harmful contaminant in the liquefied foodsample, and producing a visual cue upon recognition of the harmfulcontaminant.

In preferred embodiment of the present invention, the food testingdevice can further include a liquefier operatively associated with saidvessel for converting an unliquefied food sample into a liquified foodsample.

In a more preferred embodiment of the present invention, the foodtesting device can further include a radiation detector disposedproximately to the vessel for indicating the presence of ionizingradiation in the food sample at amounts exceeding normal backgroundlevels to detect the presence of a radioactive agent as the harmfulcontaminant.

Referring to FIG. 1, a food testing device is shown and identifiedgenerally by reference numeral 10. The food testing device 10 ispreferably constructed to be small and compact for portability anddiscreet use, and is used to process and test small sample amounts offood and/or drinks for the presence of potentially harmful contaminantsto provide enhanced consumption safety and prevent illnesses, injury andpossibly death due to food poisoning.

Representative examples of potentially harmful contaminants include anyof those selected from persistent toxic substances that can remainviable for long periods of time in food and water, and can readily bespread through food and drink products to the end consumer. Suchpersistent toxic substances can be chemical agents (e.g., heavy metals,pesticides, toxins, chemical substances), biological agents (e.g.,pathogens, disease infections) or radioactive agents or combinationsthereof, and/or specific allergens that may trigger adverse reactions incertain sizable portions of the population.

The food testing device 10 comprises a base or substrate 12 supporting aliquefier assembly 14 for converting food into a liquid or puree form.The liquefier assembly 14 includes a power switch 16 for electricalconnection to a power source (not shown) such as a rechargeable battery,a vessel 18 for receiving and holding a disposable sample container 20,and a blade assembly 22 connected through a hinge 24 to the vessel 18.The container 30 is adapted to receive and retain a small sample amountof food and/or liquid. The food testing device 10 can further include anoptional container dispenser (not shown) located in the base 12 fordispensing a fresh disposable sample container 20 for each testing use.

The blade assembly 22 includes a blade housing 30 and acentrally-located spindle 26 extending from the blade housing 30 with aplurality of mixing blades 28 disposed therearound. The mixing blades 28are configured to cut and break up any solids that may be present in thefood sample and convert it into a puree form. The mixing blades 28 canbe detached from the spindle 26 for cleaning. A motor (not shown)contained in the blade housing 30 mechanically drives the spindle 26 andthe plurality of blades 28 during operation.

The food testing device includes a radiation detector assembly 32disposed around the vessel 18. The radiation detector assembly 32 isdesigned to detect and measure the presence of any ionizing radiationemanating from the food and/or liquid sample at amounts exceeding normalbackground radiation levels. The radiation detector assembly 32 informsthe consumer of the amount of the ionizing radiation emanating from thefood sample.

This information is conveyed through an indicator assembly 34 comprisinga “safe” indicator light 36 and an “unsafe” indicator light 38.Alternatively, the indicator assembly can be a measurement gauge. If thelevel of the ionizing radiation is detected above a predeterminedthreshold for safety, the unsafe indicator 38 is activated to warn theconsumer to avoid the respective food due to elevated levels ofradioactivity, and possible contaminating presence of a radioactiveagent. For example, generally caesium and strontium are found in milk,in which the safe levels of radioactivity should be below 1 kBq/Kg (oneKilobecquerel/Kilogram). Note that all other isotopes should have aradioactivity below 1 KBq/kg.

The radiation detection assembly 32 can be selected from any suitableionization radiation detection devices including a Geiger counter, ascintillation counter, a photo multiplier, an ionization chamber, asemiconductor detector, a radiation dosimeter, and combinations thereof.

In an alternative embodiment, the radiation detection assembly can be inthe form of a radioactive test assay utilizing chemical reagents toindicate the presence of a radioactive agent through reaction with theionizing radiation emanating from the food sample. The radioactive testassay can be held proximate the food sample to detect dangerous ionizingradiation, in which the assay changes color or produces a visual cue asa visual indication of dangerous radioactivity contaminating the foodsample.

The food testing device 10 further includes a test supply compartment 40for accommodating and storing test assays (not shown) preferably in theform of dipstick assays including chromatographic assays such as flowthrough assays and lateral flow assays. Such test assays have beenadapted for detecting specific components in a food sample through asimple one step process. A storage area 42 provides for holding the testassays during testing of the food sample as will be describedhereinafter. The test assays are configured to receive a portion of thefood sample from the liquefier assembly 14 after processing, to test thefood sample for contaminants. A timer 44 with control buttons 46 allowsthe consumer to determine and monitor the completion of the test assaysto check results.

The test assays are preferably in the form of a dipstick assay includingchromatographic assays such as flow through assays or lateral flowassays, or other dipstick assays. Most preferably, the test assay is alateral flow assay. Such test assays are known in the art, and canreadily be constructed and designed by those skilled in the art todetect specific contaminants. They are also commercially available fromvarious suppliers including, for example, the Food Safety segment ofNeogen Corporation of Lansing, Mich. As discussed above the use oflateral flow assays yields a relatively simple one-step analysis processthat can be implemented by inexperienced users. Suitable examples ofcommercial products include the REVEAL™ line of test assays marketed byNeogen Corp. for detecting E. coli O157:H7, Listeria spp., Salmonellaspp., Salmonella enteritidis, peanut allergen, aflatoxin, deoxynivalenoland other dangerous substances in food and animal feed.

Generally, a lateral flow assay typically includes an elongated stick orrectangular component, often of paper, nitrocellulose or other porousinert material, upon which are printed stripes or layers of assayreagents having particular affinity for a target substance (i.e.,harmful contaminant). The lateral flow assay includes a sample end,which is dipped into a sample, and the fluid is drawn along the strip bycapillary action. As the sample passes the zones of assay reagents,chemical reactions occur which may result in visual cues or colorchanges, which can be in the form of one or more stripes, for example,to indicate the presence of one or more target substances orcontaminants, in this example. Such lateral flow assays and assayreagents are known in the art.

A variety of reagents can be used to detect a range of analytes to alertthe user of the presence of harmful contaminants and food allergens infoodstuffs, and can be derived from immunodiagnostic, enzymatic, lateralflow immunochromatography or chemistry type reactions. The reagent usedin the test assays of the present invention can be any substance havinga specific affinity for a target substance or analyte corresponding tofood allergens or toxic substances, including chemical agents andbiological agents that may be present in food stuffs and represent adangerous threat to the health of the consumer.

Suitable reagents can be selected from those that can provide detectionfor harmful contaminants such as biological agents including, but notlimited to, pathogens such as Escherichia spp. (e.g., E. coli O157:H7),Bacillus spp. (e.g., Bacillus anthracis and Bacillus cereus),Clostridium spp. (e.g., Clostridium botulinum and Clostridiumperfringens), Campylobacter spp. (e.g., Campylobacter jejuni),Salmonella spp. (Salmonella enteritidis and Salmonella typhi), Listeriamonocytogenes, Shigella spp., Streptococcus spp., Vibrio spp. (e.g.,Vibrio cholerae, Vibrio parahemolyticus, and Vibrio vulnificus),Staphylococcus spp (e.g., Staphylococcus aureus), Yersinia spp. (e.g,Yersinia enterocolitica), and the like, and chemical agents including,but not limited to, pesticides, toxins including ricin, botulin,aflatoxins, pyrrolizidine alkaloids, scombrotoxins, neurotoxin,mycotoxins such as ochratoxin A toxins, patulin toxins, fusarium toxins(e.g., fumonisins, trichothecenes including deoxynivalenol andzearelenone), and marine toxins such as ciguatera toxin, shellfishtoxin, and tetrodotoxin, cyanide, nicotine, dioxin, polychlorinatedphenyls, furans, heavy metals such as arsenic, lead, and mercury,histamine, histadine, and the like. The reagents can further be selectedfrom those that can detect allergens such as those found in almonds,eggs, gliadin, milk, peanut, soy residues, and the like.

In a further embodiment of the present invention, suitable reagents canbe selected from those that can provide detection for harmfulcontaminants such as radioactive agents including, but not limited to,radioactive isotopes of uranium, cesium, xenon, iodine, potassium,strontium, plutonium, iridium, and thorium.

Referring to FIG. 2, the food testing device 10 includes a recessed area48 for accommodating the liquefier assembly 14. As discussed previously,the disposable container 20 holding the food sample, is retained in thevessel 18 of the liquefier assembly 14. The vessel 18 is located in asample well 50 of the recessed area 48. The radiation detector assembly32 includes an ionizing radiation sensor 52 extending along the samplewell 50 around the vessel 18. The blade housing 30 of the blade assembly22 is movable about the hinge 24 between open and closed positions. Inthe open position, the blade housing 30 occupies a holding well 54 ofthe recessed area 48. In the closed position, the blade housing 30couples with the vessel 18 and encloses the disposable container 20. Themixing blades 28 draw into contact with the food sample held within thecontainer 20.

Once the housing 30 is securely coupled to the vessel 18, the bladeassembly 22 is activated through the power switch 16. The mixing blades28 are driven for a sufficient time to breakup the food sample andconvert it into a soft paste or thick liquid form. During the blendingof the food sample, the radiation detector assembly 32 can be used tomeasure the ionizing radiation in the food sample. The indicatorassembly 34 (see FIG. 1) determines whether the measured ionizingradiation exceeds normal background radiation levels, and alertsaccordingly. Thereafter, the blade housing 30 is moved to an openposition, and the mixing blades 28 are withdrawn from the container 20.A test assay can be implemented to analyze the food sample from thecontainer as will be described hereinafter.

Referring to FIG. 3, a test assay is shown in the form of a lateral flowassay 56 for a preferred embodiment of the present invention. Thelateral flow assay 56 is illustrated as an exploded assembly view. Thelateral flow assay 56 can be fabricated to test for a single analyte ormultiple analytes. The results of the assay 56 can be visually detectedor machine-readable using suitable optical readers or scanners incombination with appropriate software programs. While the lateral flowassay 56 shown in FIG. 3 represents only one embodiment, it will beunderstood that the present invention is not limited as such.

As shown in FIG. 3, the lateral flow assay includes a sample pad 58 incontact with a reagent pad 60. The reagent pad 60 is in fluidcommunication with a membrane 62 comprising a test zone 64. The membrane62 is in fluid communication with a waste reservoir 66. The sample pad58, the reagent pad 60, the membrane 62 and the waste reservoir 66 areinserted and sandwiched between a cover strip 68 and a backing strip 70.

The sample pad 58 is disposed at the sample input end of the lateralflow assay 56. The sample pad 58 is dipped into the food sample, aportion of which is drawn through capillary action into the sample pad58. The sample is then wicked from the sample pad 58 through the reagentpad 60, which contains reagents (e.g., antibodies) specific for a targetsubstance or analyte representing the harmful food contaminant,conjugated to labeled or colored particles. If the target substance orcontaminant is present, the target substance or contaminant binds to theparticle conjugated reagent. The target substance-reagent-particlecomplex then leaves the reagent zone and travels through the membrane 62into the test zone 64 thereof. The test zone 64 contains fixedanti-target substance reagents that captures the complex, and produce avisible cue such as a colored line 65. The remainder of the samplecontinues to migrate to the end of the membrane 62 where it is depositedinto the waste reservoir 66.

The reagent pad 60 can further include a control immune complex that iseluted by the sample regardless of the presence of the target substance.The control conjugate migrates through the membrane 62 to the controlzone where it forms a second visible cue such as a colored line 67.Regardless of the presence or absence of the target substance, thecontrol line forms in the control zone to ensure the test assay isworking properly. Note that a plurality of assays such as lateral flowassays 56 in the form of dipsticks can be held in the storage area 42,each for testing for a single contaminant. However, it is preferred thateach test assay be capable of testing for a plurality of contaminants tothe greatest extent possible.

The forgoing discussion discloses and describes merely exemplaryembodiments of the present invention. One skilled in the art willreadily recognize from such discussion, and from the accompanyingclaims, that various changes, modifications, and variations can be madetherein without departing from the spirit and scope of the invention asdefined in the following claims.

1-20. (canceled) 21: A method for providing a device for testing for thepresence of harmful contaminants in a food sample, comprising: formingin a substrate a vessel comprising an open top and an interior cavity incommunication with the open top, wherein said interior cavity is adaptedfor receiving and accommodating a disposable container to hold a foodsample; hingedly connecting a mechanical liquefier to the open top ofsaid vessel, said mechanical liquefier being movable to a closedposition for sealing the open top of the vessel; configuring saidmechanical liquefier with a blade assembly insertable into a disposablecontainer in said interior cavity of said vessel in the closed positionfor mechanically converting the food sample into a a liquefied form;installing a radiation detector into said substrate proximate saidvessel for indicating the presence of ionizing radiation in the foodsample at amounts exceeding normal background levels to detect thepresence of a radioactive agent as the harmful contaminant; and formingin said substrate a test assay supply compartment for containing atleast one test assay, the test assay comprising at least one assayreagent having an affinity for at least one harmful contaminant. 22.(canceled) 23: A method for testing the presence of harmful contaminantsin a food sample, comprising the steps of: liquefying the food sample toyield a liquefied food sample; and implementing at least one test assaycomprising an assay reagent having an affinity for at least one harmfulcontaminant and capable of both detecting and visually indicating thepresence of the harmful contaminant in the liquefied food sample. 24:The method of claim 23, further comprising the step of measuring theionizing radiation emanating from the liquefied food sample for thepresence of amounts exceeding normal background levels. 25: A method forproviding a device for testing for the presence of harmful contaminantsin a food sample, comprising: forming in a substrate a vessel comprisingan interior receiving area having an open top, wherein said interiorreceiving area is adapted for receiving a disposable sample container tohold a food sample; hingedly connecting a mechanical liquefier to theopen top of said vessel, said mechanical liquefier being movable to aclosed position for sealing the open top of the vessel; configuring saidmechanical liquefier with a blade assembly insertable into a samplecontainer held in said interior receiving area of said vessel in theclosed position for mechanically converting the food sample into aliquefied form; installing a radiation detector into said substrateproximate said vessel for indicating the presence of ionizing radiationin the food sample at amounts exceeding normal background levels todetect the presence of a radioactive agent as a harmful contaminant;installing into said substrate a display device operatively associatedwith the radiation detector for informing a user of the presence of aradioactive agent; forming in said substrate a test assay supplycompartment for containing at least one test assay, the test assaycomprising at least one assay reagent having an affinity for at leastone harmful contaminant; and installing in said substrate a timer fortracking and measuring the time necessary to complete the detectionprocess of the corresponding assay.